Manufacture of integrated circuit packages may involve, among other processes, the installation of heat spreaders onto the package. During an installation process, a heat spreader lid may be adhered to a substrate while the package is mounted in a process carrier. The lid may be affixed to the substrate using an adhesive and an interface material may be applied between the die and the heat spreader. Thermal conductivity between the heat spreader and the die may be dependent on the application force on the lid during curing of the interface material. A bridge clip is typically used to secure the package in the process carrier and apply force to the heat spreader while the adhesive and interface material is cured. To ensure proper heat transfer from the substrate to the heat spreader, the force asserted by the bridge clip should be maintained within an appropriate range. Examples of bridge clips may be referenced in United States Patent Application entitled “BRIDGE CLIP WITH REINFORCED STIFFENER”, having application Ser. No. 10/262,407, filed Sep. 30, 2002 and assigned to same assignee as the present application.
In some packaging situations, instead of the die being located near the center of the substrate, the die may be mounted off-center. One problem is that for these off-center located die, additional force may be desirable toward the side of the heat spreader with the die because the interface material may expand when curing at an elevated temperature. Conventional bridge clips may apply a more centralized force resulting in possible deformation of the heat spreader and reduced thermal conductivity between the heat spreader and the off-center die.
In some other packaging situations, a higher force may be needed to hold the heat spreader in place during curing. The use of higher force bridge clips generally provide a less uniform force reducing the thermal conductivity for center located die. Furthermore, the use of higher force bridge clips may deform the heat spreader, especially when curing the interface material at an elevated temperature.
Thus there is a general need for an improved bridge clip and method for holding a package in a carrier during curing. What is also needed is a bridge clip and method for securing a heat spreader over an off-center die. What is also needed is a bridge clip and method that provides an off-center force on a heat spreader when curing at an elevated temperature. What is also needed is a bridge clip and method that provides a more uniform force on a heat spreader. What is also needed is a bridge clip and method that may reduce the deformation of the heat spreader when curing at an elevated temperature.